Field of the Invention
This invention pertains to a poker vibrator.
Poker vibrators of this type are used to compress fresh concrete by attaching a vibrator body or housing to a protective tube. The vibrator body contains an eccentric weight rotated by an electric motor. In order to produce a compression frequency suitable for the fresh concrete, the motor must rotate with a very high rate of rotation, for example 12,000 RPM. This requires a higher electrical frequency compared to normal commercial power frequencies. To produce the increased electrical frequency, a frequency transformer is connected upstream of the electric motor, increasing the commercial power frequency from 50 Hertz to, for example, 200 Hertz.
There are poker vibrators wherein the protective tube is designed as an operating tube at the same time, having a length of a few meters. A switch housing is attached to the end of the protective tube opposite the vibrator housing. This switch housing contains a line switch. An electric cable runs from the switch housing to a plug that can be inserted into a conventional frequency transformer. The disadvantages in operating a poker vibrator of this kind, which are a consequence of the separate frequency transformer that is very cumbersome and difficult to handle, have resulted in the development of a poker vibrator that combines the frequency transformer with the switch in a miniaturized switch housing. This type of poker vibrator is described in EP 0 604 723 and has proven itself to be outstanding in practice. In particular, the device is very easy to operate since there is no longer a separate frequency transformer.
However, in order to integrate the frequency transformer into the switch housing, it was necessary to make the switch housing somewhat larger, which can be a disadvantage in pulling it around and with its portability at the construction site. In particular, it is possible for the somewhat enlarged switch housing to get caught on concrete reinforcement bars. Also, the switch housing with the integrated frequency transformer has a considerable weight so that constantly pulling the switch housing around can be difficult during work.
U.S. Pat. No. 5,202,612 portrays a poker vibrator that has an electric motor in a vibrator housing that is provided a power current through an electric power feed system. This current has an electrical frequency that deviates from the commercial power frequency. In the cable constituting the electric power feed system, there is first of all a switch and secondly a frequency transformer separately located from the switch.
In GB-A-2 279 184, a power plug is described with an integrated switch to interrupt the current feed.
DE 197 22 107 portrays a cable drum with an integrated frequency transformer. A power plug from a poker vibrator that requires a frequency produced from the frequency transformer can be inserted into an outlet in the cable drum.
The objective of this invention is to provide a poker vibrator that is even easier to handle, whose portability in particular is improved and whose weight that has to be moved around by the user is reduced.
The solution to this objective is provided by the poker vibrator of the present invention. Advantageous developments and embodiments of the invention can also be found in the following description.
A poker vibrator is characterized in that at least some of the components of the frequency transformer are located inside the vibrator housing or the plug housing. There are essentially two concepts of this embodiment form:
All components of the frequency transformer are integrated into the vibrator housing;
All components of the frequency transformer are integrated into the plug housing; or
The components of the frequency transformer are built into different areas of the poker vibrator.
Numerous advantages arise from the above for the construction and operation of the poker vibrator. These will be explained in detail later in the description of the embodiment forms. The essential feature is that the frequency transformer is no longer integrated into the switch housing, resulting in the advantage that the housing is very light and xe2x80x9cslipperyxe2x80x9d, or can be slid again due to its low weight and small dimensions. In operating the poker vibrator, this results in the advantage that the switch housing can be pulled from behind when working with the operating tube.
Secondly, the arrangement of the frequency transformer""s components at certain points in the poker vibrator offers the ability to install the components at targeted locations where it is especially beneficial for them to be kept. Thus, it is especially advantageous if a power component that produces a lot of heat during operation is kept in the vibrator housing that is dipped into the wet concrete, since in this way an especially effective cooling is possible.
It is not necessary that the invention variations have the switch located in its own switch housing. The switch can also be integrated into the plug housing, into the protective tube or into the vibrator housing.
The poker vibrator of the present invention also defines an embodiment form in which the frequency transformer and the switch are kept in different housings, namely in this case in a coupling and in a switch housing, respectively. This makes it possible to optimize the weight distribution at the poker vibrator and allows a shape for better portability. This can be done in a way that integrates the switch into the plug housing, whereas the frequency transformer is located in the coupling between the protective tube and the electric cable.
In another variation of the invention at least some of the components of the frequency transformer are located in a transformer housing provided between the switch housing and the power plug. This also makes it possible to optimize the weight distribution and external shape of the poker vibrator.
The invention also contemplates still another embodiment form in which at least some of the components of the frequency transformer are located in the protective tube and this portion of the components is not integrated into the switch housing. This makes it possible, for example for a poker vibrator from EP 0 604 723, to remove at least some of the components of the frequency transformer from the switch housing described there and to locate them at other points in the protective tube. This makes it possible for the switch housing to be shaped like a streamline, resulting in the improvement of the poker vibrator""s sliding ability.